Myelopathy

The title of this page consists of two parts. The first is named Myelopathy which means damage to the spinal cord and the resulting malfunction. The second part (Stenosis) of the title refers to the bony canal (the spinal column) that the spinal cord resides in. Cervical (neck) spinal stenosis can result in Myelopathy and the associated symptoms. However, there is a segment of the population that has spinal stenosis without any symptoms. This group of patient may have higher risk to develop myelopathy. Myelopathy is a serious disease and is progressive. There is no doubt that it needs treatment and should not be neglected. Furthermore, follow-up studies indicate that early treatment result in better outcome as compared with neglected cases which may have dire consequences.

Prior to the discussion of the disease, diagnosis, and treatment, the basics of spinal degeneration should be understood for better understanding of the process. As the human body ages, many of our organs go through a very slow process of degeneration. Weather this is natural process or an illness is a controversial issue but the changes may or may not lead to dysfunction and disability. Arthritis is one form of degeneration and almost all of us will have arthritis after the age of 60. However, not all of us will have symptoms and so arthritis or spinal degeneration may not be a real disease, but a natural process of aging. The entire process begins with the natural loss of water content from our organs. This again is a natural process and results in consequences in all of our systems. The process begins as the intervertebral discs loss water content. The disc could be compared to a tire full of air (in our case water) acting as a cushion between many structures (the bony spinal segments). As the tire losses air (the disc loses water) its ability to hold the structures apart, provide stability, and cushion the structures decreases. This is when we see slight movement or instability between segments in our spine. On an X-ray we may detect a decreased height to the intervertebral disc. As our body senses this instability, the bony structure attempts to stabilize itself. The only thing our bones know to best is to make more bone. So little pieces of bones are produces around the joints, the disc spaces, or the nerves. In the field of orthopaedics we call them bone spurs which are the sign of arthritis and degeneration. Also known as wear and tear in the spine. Another process which occurs often is bulging of the discs (as the tire loses air it will bulge out) or herniation. In most cases arthritis does not produce too many symptoms but leads to aching and stiffness in the morning. Patients may describe stiffness when waking up in the morning which gets better later on in the day. Anti-inflammatory medications work well for this very common condition. A small subset of patients will develop bone spurs in close proximity to neural structures and produce neurologic symptoms. One common problem is narrowing of the canals which transmit the nerves out of our spine (also called foraminal stenosis). Also, disc herniation and bulging which puts pressure over the nerve may contribute to symptoms. However if the pressure is placed on the spinal cord itself (as opposed to the nerve) other symptoms may develop. Myelopathy refers to pressure on the spinal cord which produces dysfunction in the arms and legs.

Myelopathy is a serious dysfunction of the spinal cord that develops as a result of spinal stenosis which results from arthritis and degeneration. Patients may present with very subtle complaints or very sever disability like inability to walk.

Some of the symptoms of myelopathy may include:

Difficulty walking

Unbalanced, uncoordinated walking

Heavy feeling in the legs

Difficulty with quick movements and changes in direction

Difficulty with precise movements of the hands and arms including buttoning shirts, writing or typing

A subtle sign may include changes in hand writing

Intermittent pain or electric feeling running down the arms and legs

Arm pain which is called radiculopathy. However, arm pain is only one part of the whole problem

If the condition is allowed to progress, the following symptoms and signs may develop:

Inability to walk

Numbness in the arm and legs

Inability to control bowel and bladder function

Inability to sense the position of extremity in space

The diagnosis of this condition may be very easy if presented at a late stage when patient cannot walk or severe symptoms are present. However, this could be one of the most challenging diseases to diagnose. The history and physical examination starts any initial visit to the spine surgeon. This is the time that most disease processes are diagnosed and a treatment plan is laid down. During the physical examination the spine surgeon will be looking for subtle signs for diagnosis. This examination will include testing of sensation, muscle strength, and reflexes. Other aspects include coordination in walking. Sensation around the rectum, as well as the tone of anus is important test and dysfunction may mean advanced disease.

The diagnostic process and evaluation usually continues with tests to delineate the location of pressure and its extent. We begin with X-rays of the neck to study the alignment and gross architecture. Generally this test is not specific but will allow the identification of arthritis and spinal degeneration. If suspected, we then continue with an MRI scan since this test is non-invasive and very accurate. The MRI may show spinal stenosis, disc herniation, or pressure from bony spurs. Any one or all of these changes may be seen on the MRI. The MRI has another advantage by showing any changes within the substance of the spinal cord itself. These changes are referred to as Myelomalacia and may signify a long standing process. However, Myelomalacia may be present with other disease processes as well or be an incidental finding with no consequence. The diagnostic process may end at this point or if it is still questioned, other tests may be ordered. This may include a Myelogram, and later supplemented by a CT scan. Every test increases the accuracy of diagnosis but also increases the associated risks. To decrease the risks associated with invasive tests, we plan a strategy and sequence of testing. At this stage, the judgment and knowledge of your spine surgeon plays a crucial role in your treatment. Most of these tests can be ordered by any physician, however only your spine surgeon can understand the disease process, the significance of the findings, and propose a logical treatment plan.

The treatment of Myelopathy is mostly surgical. Follow-up studies show the slow progressive nature of this disease. For this reason, we treat this disease relatively early and aggressively. The pressure over the spinal cord must be removed to stop progression and attempt to regain function. After evaluation of all diagnostic studies a surgical strategy is planned to best treat the condition. The basic differences between the available surgical procedures is the approach to the spine. The Spine can be approached from the front or from the back.

The procedure from the front was developed in the 1950′s and is still used today with some modifications. Once the spine is approached from the front two different procedures can be performed. One of the procedures include removal of the disc/s and placement of bone to fuse the segment. After placement of the bone, a Titanium plate and screws are supplemented to provide stability until the bony segments fuse. By removing the disc/s, the pressure over the spinal cord is removed as well. This procedure is called Anterior Cervical Discectomy and Fusion or ACDF. This procedure can be performed on one, two, or three levels. The more levels performed, the higher the risk of complications and difficult the procedure. Another option is Anterior Cervical Corpectomy and Strut Grafting. This procedure is similar to Discectomy with fusion, however here, we remove more bone but the surgical principles are the same.

The procedures which approach the spine from the back include Cervical Laminectomy, and Cervical Laminoplasty. The basic principle in Cervical laminectomy, is the removal of the bony roof of the spinal canal. By removing the bones in the back of the spine more room is created for the spinal cord. Generally, when more than three spinal segments are involved the spine is approached from the back. This approach allows the release of more levels. Other considerations in choosing this approach is the posture of the neck but this discussion can get lengthy and very technical. Another factor to consider is development of deformity from this procedure. Removal of bone from the back of the spine may render it weak and deformity could gradually result. In children, this problem is much more significant and laminectomy is usually avoided in that patient population. To avoid the risk of developing a deformity the bony elements of the spine can be fused with the obvious consequence of losing motion. To avoid development of deformity and loss of motion the Japanese surgeons developed a procedure called Laminoplasty. The basic principle is the same as for Laminectomy. Both procedures create more room for the spinal cord from the back, but with Laminoplasty the roof is elevated while keeping one side of the roof as a hinge. This maintains more stability, preserves motion, but with the higher risk of developing post-operative pain or discomfort. Some studies suggest better results with laminoplasty, however the choice of these procedures are still surgeon dependent based on teaching theory and beliefs. Patients should refer to specific sections underlined above for more information regarding these procedures. Still, the choice to operate should be discussed carefully with the surgeon. After considering the diagnostic studies and physical findings a surgical plan will be introduces to best serve the patients’ needs. The procedure of choice is usually not clear cut and the decision making process is very complicated. The factors involved, include the severity of disease, general medical condition of the patient, history of other procedures, posture of the neck, involvement of other neural structures, and many others. Only your spine surgeon can consider all these facts based on his knowledge, experience, and judgment.